Makes 1 cocktail
From Vincenzo Marianella
1/2 ounce good-quality reposado tequila, preferably 4 Copas
3/4 ounce St-Germain elderflower liqueur
1 ounce ruby grapefruit juice
2 to 2 1/2 ounces Champagne or prosecco
Combine the tequila, St-Germain and grapefruit juice in a cocktail shaker with ice. Strain into a cocktail flute. Top with Champagne. Quickly stir; then serve immediately.